1. Technical Field
The present invention relates to an electronic timepiece that receives signals sent from GPS satellites or other positioning satellites and derives the current date and time from the signals, and to a time adjustment method.
2. Related Art
GPS satellites with known orbits around the Earth are used in the GPS system, which is a system for determining one's position, and each GPS satellite carries an atomic clock. Each GPS satellite therefore also keeps extremely precise time information (also referred to as the GPS time or satellite time).
Mobile electronic devices having a unit that uses time information contained in navigation data sent from GPS satellites to correct internal time data kept by a timekeeping unit are known from the literature. See, for example, Japanese Unexamined Patent Appl. Pub. JP-A-2006-194697.
JP-A-2006-194697 teaches a control method that uses a UV sensor to determine an indoor or outdoor location, and receives GPS signals only when outdoors.
JP-A-2006-194697 describes a method of selectively receiving outdoors navigation data sent from a satellite that is difficult to receive indoors, but there are situations in which reception is difficult due to indoor/outdoor recognition errors caused by indoor lighting, or the effect of multipath interference or a location with a narrow open angle to the zenith due to the effect of tall buildings when outdoors.